JP3338362B2 - Wireless telephone - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a portable radio telephone, and more particularly, to a technique for connecting to a new radio base station accompanying movement.

[0002]

2. Description of the Related Art A fixedly installed radio base station (CS)
(PS: Portable wireless telephone)
In a mobile communication system such as a personal handy phone system (PHS) that realizes a telephone call by a mobile phone, a portable terminal is typified by "reconnection" of a wireless base station at the time of handover (mobile call). With the movement of the user who uses, the portable device specifies a new relay radio base station that can secure a reception level (RSSI) of a certain value or more, and establishes a link with the radio base station. There is a need.

[0003] FIG. 7 is a diagram showing a situation where a connection change for handover is required. Here, a portable device PS moving to another wireless zone while maintaining a call state is shown. In order to perform such a connection change, the conventional portable device detects that the reception level for the currently connected wireless base station has become lower than a certain threshold value, For a suitable wireless base station. As a result, if multiple radio base stations
If the reception level exceeds a certain reception level, connection is attempted in descending order of the reception level among the radio base stations.

For example, first, an attempt is made to connect to a radio base station having the highest reception level. As a result, when a communication channel with the radio base station is occupied, that is, the number of connectable radio base stations (for example, (3) portable devices have already been connected, this time, an attempt is made to connect to a wireless base station having the next highest reception level. As such, within a certain time limit (eg, 6 seconds), the same attempt is repeated until a successful connection to another good wireless base station is made.

[0005] In this way, the conventional portable device attempts to connect to another radio base station in descending order of the reception level in order to maintain a good communication even if a little, so that a new relay radio base station is established. The station is specified.

[0006]

However, in the conventional method of specifying a radio base station, for example, calls by many portable devices are concentrated in a narrow area such as a downtown area or a station square. In this case, the connection fails despite the presence of another good wireless base station, that is, the communication line is unnecessarily occupied (hereinafter referred to as "occurrence of a hidden wireless base station. ").

For a plurality of portable devices located close to each other, a best list of wireless base stations to be newly connected, that is, a list in which a plurality of wireless base stations as connection candidates are arranged in descending order of reception level, Are almost equal, so that each of the plurality of portable devices times out while trying to connect to the same wireless base station positioned higher in the best list. In other words, if the top teams on the best list are crowded, the above time limit elapses while trying to connect to the wireless base stations of those top teams, and any portable device will be placed on the bottom of the best list. The time-out occurs while no attempt is made to the radio base station corresponding to the team.

[0008] For example, it is assumed that a portable device that has a best list of ten wireless base stations performs connection switching in front of a station where many wireless base stations are installed in close proximity. . However, due to the above time limit, the number of wireless base stations to which the portable device can try to connect is limited to, at most, the top three to five in the best list. Therefore, if the communication channels are not vacant for all of the upper three to five wireless base stations, even if there are vacant channels in the lower five wireless base stations, none of such portable devices can be connected. And the handover fails. At this time, if switching back to the original radio base station also fails, the call is no longer disconnected.

The present invention has been made in view of the above problems, and has as its object to provide a portable device in which a hidden wireless base station is hardly generated when a new wireless base station to be connected is specified. And

[0010]

SUMMARY OF THE INVENTION In order to achieve the above object, a wireless telephone according to the present invention is a mobile telephone that performs communication through connection with a wireless base station, and is a candidate for connection. Means for detecting a wireless base station, means for creating a best list arranged in the descending order of the reception level for all the detected wireless base stations, and an upper order in which the created best list is located higher than a predetermined order. When the radio base station is divided into a group and a lower group located in a lower order, the radio base stations belonging to the best list are arranged in an order in which at least one radio base station belonging to the lower group has priority over at least one radio base station belonging to the upper group. Selecting means for selecting a station, connecting means for trying to connect to the selected radio base station, and when the connection by the connecting means succeeds, the selecting means To terminate the selection that, if the connection fails due to the connection means is characterized by having a repeating control means for causing repeated and connected by the connection means and selected by said selection means.

In other words, when a new relay radio base station is specified along with the movement of a radio telephone, not only a radio base station having a high reception level but also a plurality of candidate radio base stations is selected from among a plurality of candidate radio base stations. A wireless base station having a low reception level, whose order is likely to fluctuate, is intentionally selected to attempt connection.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG.
FIG. 2 is a hardware configuration diagram of a portable device 100 that is an HS wireless telephone. The portable device 100 includes an antenna 101, a high frequency unit 102, a modem unit 103, a TDMA unit 104, a COD
EC unit 105, microphone 106, speaker 107, bus 1
08, CPU 109, random number generation unit 110, memory unit 11
1 and an input / output unit 114.

The high-frequency section 102 performs amplification of radio waves at 1.9 GHz, switching between transmission and reception, measurement of RSSI, and the like.
The modem unit 103 performs modulation and demodulation using π / 4 shift QPSK, the TDMA unit 104 performs multiplexing, demultiplexing, and access control using TDMA / TDD.
Reference numeral 05 performs audio processing by A / D conversion, D / A conversion, and encoding / decoding.

The CPU 109 is a microcomputer having a built-in timer function. The CPU 109 controls each component based on a control program stored in a control program storage unit 113 of the memory unit 111, thereby changing the connection according to the present invention. Or make the portable device 100 function as a PHS wireless telephone. The random number generation unit 110 generates an 8-bit random number based on a random number table stored in advance.

The memory unit 111 includes a RAM, a ROM, and the like, and has a best list storage unit 112 and a control program storage unit 113 in addition to a temporary work storage area. The best list storage unit 112 is an area for storing a best list that is temporarily created when a connection is changed, and specifically, an identification number (CS-ID) of a wireless base station that is a connection candidate. ID) are stored. The control program storage unit 113 stores a program for causing the portable device 100 to function as a PHS wireless telephone in advance, and the program includes a connection switching procedure shown in a flowchart described later.

The input / output unit 114 is an LCD, operation keys, and the like, and functions as a man-machine interface. Next, the operation of the portable device 100 configured as described above will be described. FIG. 2 is a flowchart showing an operation procedure when the portable device 100 changes the connection of the wireless base station for handover (H / O). FIG. 3 is a flowchart showing details of steps S207 and S208 shown in FIG.

Now, it is assumed that the portable device 100 is in a call state via the wireless base station when the location registration is performed (step S200). In this state, the portable device 100 periodically monitors whether it is necessary to change the connection for the handover during the control for the call (step S201). Specifically, the RSSI for the radio base station is periodically compared with an H / O activation level L2 stored in advance. Here, the H / O activation level L2 refers to an RSSI serving as a lower threshold value at which a process for H / O should be activated, and has been previously transmitted from the radio base station and stored in the memory unit 111. Value.

As a result, if the RSSI becomes lower than the H / O activation level L2, the portable device 100
The communication is interrupted, and a connection change for handover is attempted (steps S202 to S213). For this purpose, the portable device 100 first sets the internal timer to 6 seconds, starts the timer, and then sets all (N) that can secure RSSI exceeding the H / O destination selection level L1 stored in advance.
Wireless base stations are identified (step S202). More specifically, the CPU 109 obtains, from the TDMA unit 104, the identification numbers of all the radio base stations whose RSSIs measured by the modem unit 103 exceed the H / O destination selection level L1, and stores them in the memory unit 111.

Here, the H / O destination selection level L1 is H
RSSI is a lower threshold value that is allowed to be selected as a new radio base station for / O, and the H / O activation level is set so as to have hysteresis for securing a stable communication state. It is set to a level higher than L2, and is a value previously sent from the wireless base station and stored in the memory unit 111.

FIG. 4 is an example of a best list in which all the radio base stations detected by the portable device 100 are arranged in descending order of RSSI. Here, the identification numbers are assigned to CS1, CS2,
···, CS9. A total of seven radio base stations with RSSI higher than the H / O destination selection level L1 (CS1 to CS1)
7), one radio base station (CS9) with RSSI lower than the H / O activation level L2 is shown. The radio base station for location registration is CS9. Since the RSSI for the radio base station CS9 has fallen below the H / O activation level L2, H / O has been activated.

FIG. 5 is a location map corresponding to the best list of the radio base stations shown in FIG. 4, where one portable device (PS) 100 located at the center and nine radio base stations CS1 to CS9 are located. Each positional relationship is shown. Note that the circles (areas 1 to 9) shown in this figure indicate that the RSSI for each of the radio base stations CS1 to 9 is the H / O destination selection level L.
1 indicates a zone. For example, in this figure, the portable device (PS) 100 is located outside the area 8 formed by the radio base station CS8, which means that the RSSI for the radio base station CS8 is H / O destination in FIG. This corresponds to slightly lower than the selection level L1.

Therefore, assuming that the portable device (PS) 100 has the positional relationship shown in FIGS. 4 and 5, in step S202, the portable device 100 identifies seven wireless base stations in total. The number is detected and the memory unit 111
Will be stored temporarily. Subsequently, the portable device 100
Registers the identification numbers of the seven wireless base stations as the best lists CS1 to CS7 shown in FIG. 4 in the best list storage unit 112, and the upper and lower RSSI groups (CS1 to CS4) and the lower RSSI group (CS5 to 7) and store them separately (step S203). When the total number of the wireless base stations constituting the best list is an odd number, here, the wireless base station (C
S4) is included in the upper group.

The portable device 100 switches between the upper group and the lower group alternately until the connection succeeds or the timeout occurs.
Attempts to connect to one wireless base station belonging to the group are repeated (steps S204 to S213). That is,
First, the portable device 100 is connected to the radio base station CS of the upper group.
One is randomly selected from 1 to 4, and connection is attempted for one of them (step S208). In particular,
As shown in the flowchart of FIG.
Causes the random number generation unit 110 to generate one random number (step S220), and divides the random number R by the selectable number Nu (4 units) belonging to the upper group (R mod N
u) is determined, and one wireless base station in the order corresponding to the surplus is specified (step S221). Then, the identification number of the specified wireless base station is deleted from the registration in the upper group, and a connection change is attempted by requesting the wireless base station to establish a link channel (step S222). The reason why the radio base station is excluded from the upper group is to prevent the same radio base station from being selected again.

As a result, if the wireless base station to which the link is attempted cannot be connected because there is no available channel or the communication state is bad (step S209), the wireless base station is registered in one of the upper group and the lower group. It is determined whether a wireless base station is left (step S210) and whether the timer set in step S202 has timed out (step S211). Note that the case where the connection cannot be established specifically refers to a case where the allocation of the communication channel or the time slot is not notified from the radio base station in response to the link channel establishment request, or a case where the synchronization is performed after the allocation is performed. This applies when establishment or message transmission / reception fails.

As a result, if the wireless base station to be linked remains (step S210) and the timeout has not occurred (step S211), an attempt is made to change the connection to a new wireless base station. Repeat (Step S
205 to S211). However, in the second (even-numbered) trial, the portable device 100 randomly selects one of the lower-level radio base stations CS5 to CS7 and requests the establishment of a link channel for the one. (Step S207). The detailed procedure is as shown in the flowchart of FIG. 3, and the basic processing is the same as the processing in the upper group (step S208).

As described above, while alternately switching between the upper group and the lower group, a process of randomly selecting a wireless base station and attempting a link without duplication is repeated. Here, if the connection with the wireless base station that attempted the link is successful (step S209), the connection is changed from the wireless base station CS9 that has been connected up to the new wireless base station. The H / O processing is completed (step S213). Specifically, after establishing synchronization with the wireless base station using the communication channel and slot allocated from the new wireless base station and exchanging messages necessary for connection, the portable device 100 Transition to a call state.

On the other hand, when all the radio base stations registered in the upper group and the lower group have been deleted (step S209), or when the timeout of 6 seconds has occurred (step S211). ), Abandon further connection attempts, and switch back to the original radio base station CS9 (step S212). In this manner, when the RSSI with respect to the wireless base station to which the portable device 100 is connected falls below the H / O activation level L2, the portable device 100
A best list of wireless base stations serving as new connection candidates is created, separated into two groups, an upper group and a lower group, and one group is alternately switched, and one wireless base station is selected from the group based on a random number. Select a base station and try to change connection sequentially.

Therefore, according to the portable device 100, the selection order of the wireless base stations to be reconnected is random, and even if a plurality of portable devices are located close to each other, the same wireless base station can be selected in the same order. The problem of trying to connect by hand is avoided. Further, according to the portable device 100, the radio base stations belonging to the upper group having the higher RSSI and the radio base stations belonging to the lower group having the lower RSSI are alternately selected instead of simply selecting the radio base stations at random. Since the selection is made, link requests are issued to all the radio base stations that are selection candidates uniformly, and the problem that link requests concentrate on radio base stations with high RSSI is solved.

It should be noted that even if the portable devices are located close to each other, the radio base stations belonging to the lower group, that is, the radio base stations that are far apart, may have a slight difference in their locations between them. The RSSI greatly varies due to the influence of a located obstacle or the like.
Further, even if the radio base station belongs to a lower group, H
It is not different from a radio base station belonging to an upper group in that it is a radio base station that can secure an RSSI exceeding the / O destination selection level L1, that is, a radio base station having a qualification to be reconnected. Here, as in the present embodiment, it is meaningful to actively try to connect not only to the upper group but also to the wireless base stations belonging to the lower group.

Therefore, if a connection destination is selected from the group of wireless base stations belonging to the lower group, the random number generation unit 110 is not used as in the present embodiment, but according to a predetermined fixed selection order. Even when a link request is issued, the order of wireless base stations that are actually selected varies from one portable device to another, so that a plurality of portable devices link to the same wireless base station in the same order. A biased choice of issuing a request is avoided.

FIGS. 6 (a) to 6 (e) are diagrams showing a modification of the present embodiment with respect to the selection order of the H / O destination radio base stations, and show steps S208 and S207 shown in FIG. This corresponds to a modification of the detailed procedure. FIG. 6 (a)
FIG. 6B shows the same H / O destination wireless base station best list as that of the present embodiment again, and FIGS.
The specific selection order by the four types of modifications in the best list shown in FIG. Each of these four types of modifications is a fixed selection method that does not use random numbers.

In the method 1 shown in FIG. 6B, first, a radio base station having the highest RSSI is selected from the upper group and connection is attempted. If the connection fails, the radio base station is transmitted from the higher group. After the deletion, the wireless base station with the lowest RSSI is selected from the lower group, and a connection is attempted. If the connection fails, the procedure of deleting the wireless base station from the lower group is repeated. .

In the method 2 shown in FIG. 6C, first, a radio base station having the lowest RSSI is selected from the upper group and connection is attempted. If the connection fails, the radio base station is transferred from the upper group. After the deletion, the wireless base station with the highest RSSI is selected from the lower group, and then the connection is attempted. If the connection fails, the procedure of deleting the wireless base station from the lower group is repeated. .

In the method 3 shown in FIG. 6D, first, a radio base station having the highest RSSI is selected from the upper group and connection is attempted. If the connection fails, the radio base station is transmitted from the higher group. After the deletion, the wireless base station with the highest RSSI is selected from the lower group, and then the connection is attempted. If the connection fails, the procedure of deleting the wireless base station from the lower group is repeated. .

In the method 4 shown in FIG. 6 (e), first, a radio base station having the lowest RSSI is selected from the upper group and connection is attempted. If the connection fails, the radio base station is transferred from the higher group. After the deletion, the wireless base station with the lowest RSSI is selected from the lower group, and a connection is attempted. If the connection fails, the procedure of deleting the wireless base station from the lower group is repeated. .

The four types of modifications have a fixed selection order that does not use random numbers, and actively select not only the upper group but also the radio base stations belonging to the lower group. That is. It is to be noted that a selection method without deviation can also be obtained by combining these four types of modified examples and the random number generation unit. For example, four types of selection procedures shown in FIGS. 6A to 6E are stored in advance, and when H / O is required, one of the four types is selected using random numbers. May be determined, and connection to the wireless base station is attempted in accordance with the selection order.

Also, in the present embodiment, the best list of wireless base stations as connection candidates is divided into an upper group and a lower group with the middle order as a boundary, and the two groups are alternately switched to sequentially perform wireless communication. Although a base station has been selected, the invention is not limited to such boundary locations and number of groups. For example, the rank separating the upper group and the lower group at a ratio of 7: 3 may be used as a boundary,
It may be divided into four groups. This is because hidden wireless base stations can be avoided by a method of positively selecting not only wireless base stations having a high reception level but also wireless base stations having a low reception level.

In this embodiment, the selection order of the radio base stations for the connection change in the H / O is shown, but the selection procedure of the radio base station according to the present invention is performed in the case of such a connection change. It is not limited to, for example, when determining a new relay base station at the time of calling, or other base station when the standby base station registered in advance can not be used at the time of incoming call to the portable device It is needless to say that the present invention can be applied to a case where a decision is made. The present invention specifies a wireless base station that can be connected efficiently without generating a hidden wireless base station when connecting to any of a plurality of candidate wireless base stations with the movement of a portable device or the like. It is because it is about the procedure for.

[0039]

As is apparent from the above description, the radio telephone according to the present invention is a mobile telephone which performs communication via connection with a radio base station, and is a radio base station which is a candidate for connection. Means for detecting, for all detected wireless base stations, means for creating a best list arranged in the descending order of the reception level, an upper group and a lower group in which the created best list is positioned higher than a predetermined order When the radio base stations belonging to the lower group are divided into the lower groups, at least one radio base station belonging to the lower group is prioritized over at least one radio base station belonging to the upper group, and the radio base stations belonging to the best list are selected. Selecting means, a connecting means for trying to connect to the selected wireless base station, and selecting the selecting means when the connection by the connecting means succeeds. Is completion, when the connection fails due to the connection means is characterized by having a repeating control means for causing repeated and connected by the connection means and selected by said selection means.

Thus, when a new relay radio base station is specified in accordance with the movement of the radio telephone or the like, only the radio base station having a high reception level is selected from a plurality of candidate radio base stations. Instead, a wireless base station having a low reception level, whose order is likely to fluctuate, is intentionally selected and a connection is attempted. Therefore, the problem of occurrence of hidden radio base stations due to the concentration of connection requests on the same radio base station group having a high reception level is avoided, and even if the number of radio base stations is the same,
This has the effect of increasing the substantial number of wireless telephones that can be connected at the same time, and the effect of shortening the time until a connectable wireless base station is found.

Here, the selection means may select the radio base stations belonging to the upper group and the radio base stations belonging to the lower group alternately without overlapping. For example, the radio base stations belonging to the upper group may be selected in descending order of the reception level, and the radio base stations belonging to the lower group may be selected in descending order of the reception level.

As a result, the radio base station having the higher reception level and the radio base station having the lower reception level are selected at the same frequency. Therefore, the effect of the communication stability by selecting the radio base station having the higher reception level and the reception level can be obtained. In other words, the effect of shortening the connection time by selecting a wireless base station having a low connection rate, that is, a connection possibility is highly exhibited. Further, the selection means includes an upper group storage unit that stores identification information of the radio base stations belonging to the upper group, a lower group storage unit that stores identification information of the radio base stations belonging to the lower group, and generates a random number. A random number generator that performs
While alternately switching between the upper group storage unit and the lower group storage unit, one piece of identification information specified by a random number generated by the random number generation unit is selected from the identification information stored in each of the storage units, A selection erasure unit for erasing the storage of the selected identification information, wherein the connection unit attempts a new connection to the wireless base station corresponding to the identification information selected by the selection erasure unit. Can also.

As a result, the order of the radio base stations to be selected is random, so that even in the case of radio telephones having the same best list, the order of the radio base stations selected by them is often different. Thus, the problem of concentration of connection requests to the same wireless base station is more reliably avoided. Further, the selecting means includes:
A selection order storage unit that stores in advance a plurality of different selection orders in which a radio base station belonging to the upper group and a radio base station belonging to the lower group are not alternately selected, and a random number generation unit that generates a random number And a selection order identification unit that identifies one of the plurality of selection orders based on the generated random numbers, and a base station selection unit that selects a wireless base station according to the identified selection order. You can also.

Thus, only by generating a random number once, one of a plurality of selection procedures is randomly determined, and a radio base station having a high reception level and a radio base station having a low reception level are alternately selected. Therefore, there is an effect that a wireless base station is selected in a shorter time and without deviation. As described above, according to the present invention, the utilization rate of many base stations installed outdoors is improved, and even if the same base station is arranged, the number of radio telephones that can receive services substantially simultaneously And its practical effect is extremely large.

[Brief description of the drawings]

FIG. 1 is a hardware configuration diagram of a portable device 100 according to the present invention.

FIG. 2 is a flowchart showing an operation procedure when the portable device 100 changes connection of a wireless base station for handover.

FIG. 3 shows steps S207 and S208 shown in FIG.
6 is a flowchart showing details of the process.

FIG. 4 is an example of a best list created by the portable device 100;

FIG. 5 is a location map corresponding to the best list of the wireless base station shown in FIG. 4;

6 (a) shows an H / O destination wireless base station best list in FIG. 4, and FIGS. 6 (b) to 6 (e) show FIG.
The specific selection order by the four types of modifications in the best list shown in FIG.

FIG. 7 is a diagram showing a situation where connection change to a new radio base station is required.

[Explanation of symbols]

 REFERENCE SIGNS LIST 100 portable device 101 antenna 102 high frequency section 103 modem section 104 TDMA section 105 CODEC section 106 microphone 107 speaker 108 bus 109 CPU 110 random number generation section 111 memory section 112 best list storage section 113 control program storage section 114 input / output section

Claims (5)

(57) [Claims] 1. A mobile telephone that performs communication via a connection with a wireless base station, comprising: means for detecting a wireless base station that is a candidate for connection; Means for creating a best list arranged in descending order of the reception level; and, when the created best list is divided into an upper group positioned higher than a predetermined order and a lower group positioned lower, at least belonging to the lower group Selecting means for selecting a wireless base station belonging to the best list in an order in which one wireless base station is prioritized over at least one wireless base station belonging to an upper group; and attempting to connect to the selected wireless base station. Connection means, when the connection by the connection means succeeds, ends the selection by the selection means, and when the connection by the connection means fails, the Radio telephone, characterized in that it comprises a repetition control means for repeated selection by-option means and the connection by the connecting means. 2. When the best list is divided into an upper group located higher than the center and a lower group located lower than the best list, the best list is assigned to the radio base station and the lower group belonging to the upper group. 2. The radio telephone according to claim 1, wherein the radio base station to which the radio telephone belongs is selected alternately without overlapping. 3. The radio communication system according to claim 1, wherein the selecting unit is configured to:
3. The radio telephone according to claim 2, wherein radio base stations belonging to the lower group are selected in ascending order of the reception level. 4. An upper group storage unit for storing identification information of wireless base stations belonging to the upper group, a lower group storage unit for storing identification information of wireless base stations belonging to the lower group, A random number generation unit that generates a random number, while alternately switching between the high-order group storage unit and the low-order group storage unit, from the identification information stored in each of them, the random number generation unit identifies the random number generated by the random number generation unit. A selection erasure unit that selects one piece of identification information and erases the storage of the selected identification information, wherein the connection unit is a radio base station corresponding to the identification information selected by the selection erasure unit. 3. The wireless telephone according to claim 2, wherein an attempt is made to connect to the wireless telephone. 5. A selection order storage for preliminarily storing a plurality of different selection orders in which radio base stations belonging to the upper group and radio base stations belonging to the lower group are alternately selected without overlapping. A random number generation unit that generates a random number; a selection order identification unit that identifies one of the plurality of selection orders based on the generated random number; and a wireless base station that is selected according to the identified selection order. 3. The wireless telephone according to claim 2, further comprising a base station selector.